The electrical systems in residential, commercial and industrial applications usually include a panel board for receiving electrical power from a utility source. The power is then routed through protection devices to designated branch circuits supplying one or more loads. These protection devices are typically circuit interrupters such as circuit breakers and fuses, which are designed to interrupt the electrical current if predetermined limits of the conductors are surpassed or if other predefined fault conditions are detected on one of the protected lines or branches. In other words, circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition (e.g., a ground fault or arc fault condition).
An arcing fault is commonly defined as an electric current, often strong, brief, and luminous, in which electrons (or the current) jump across a gap in a circuit or between two electrodes. For example, lightning is a case of an electric arc between one cloud and the earth or another cloud, as are sparks caused by discharges of static electricity. There are many conditions that may cause an arcing fault. For example, corroded, worn or aging wiring, contacts, connectors or insulation, loose connections, wiring damaged by nails or staples through the insulation, and electrical stress caused by repeated overloading, lightning strikes, etc.
An Arc Fault Circuit Interrupter (AFCI) is a circuit breaker designed to trip, for example, by detecting a non-intended electrical arc and to disconnect power quickly upon detecting the arc. The AFCI device may distinguish between a working arc that may occur in the brushes of a vacuum cleaner, light switch, or other household devices, for example, and a non-working arc that can occur, for instance, in a lamp cord that has a broken conductor in the cord from overuse, for example. The AFCI device may be adapted for use in any residential and/or commercial power system environment and may be configured to detect arc faults, including both line-fault (e.g., parallel-type arcing between lines) and contact-fault (e.g., series-type arcing on the same line due to electrical discontinuity in the conductor) that may be present on a power circuit associated with the power system.
Some types of conventional circuit breakers do not include an arc fault indicator. As such, these circuit breakers do not provide any feedback to the customer or technician of what type of tripping condition has occurred in the system. Other types of conventional circuit breakers may include a mechanical arc fault indicator, such as a trip flag, for example, to indicate if an arc fault has been generated. A problem with the mechanical arc fault indicator is, for example, that variations in manufacturing may cause reliability issues for this type of system. For example, the technician may be led to a false diagnosis of the problem, leading to considerable effort to repair the problem. Mechanical indicators may typically be less cost effective and may be prone to a failure due to parts binding, missing, or being worn out. Other types of conventional circuit breakers may include a visual arc fault indicator for outputting status, health, and/or fault information associated with the circuit breaker. However, these visual arc fault indicators typically require high manufacturing tolerance requirements in terms of the mating features to hold the visual display in place within the circuit breaker. As such, these features need to be monitored frequently in production to ensure a quality product. Accordingly, a need exists for an improved method and apparatus for visually indicating a multi-pole circuit breaker has tripped.